Wind turbines are in widespread use for the generation of electrical energy. In a typical form, a multi-blade turbine is rotatably mounted on a support such as a pole or tower to be driven by surface winds, the turbine in turn driving an electrical generator coupled, for example, to electrical utility lines. The turbine can be rotated about a vertical axis of the pole or tower to compensate for shifts in wind direction.
The use of diffusers with wind turbines is also known, the objective being to increase the efficiency of converting wind energy to electrical energy. Such known diffusers are typically mounted on the support tower, and a shaft-mounted turbine rotates within the diffuser. Such an arrangement is disclosed in U.S. Pat. No. 4,075,500, which, for brevity, is incorporated herein by reference.
The improvement of this invention relates to integration of the turbine blades with a surrounding hollow cylindrical-shell rotor drum, the drum in turn being rotatably supported within a central part of the surrounding diffuser. A central hub and supporting shaft for the turbine blades is eliminated, and blade stiffness is significantly increased. The blades and rotor drum can be cast, or injection molded in a single manufacturing step.